Blender on Google Colab not finding Graphics Card
I'm also facing the same problem. I think colab is not allowing GPU to use for any commands that include "sudo" in it.

Solution I found was to install blender and then run the command to render without "sudo".

I installed blender from PPA ppa:thomas-schiex/blender

commands to execute:

!sudo add-apt-repository ppa:thomas-schiex/blender
!sudo apt-get install blender
!blender -b -P script.py filename.blend -o fileoutput -F PNG -f 1


script.py contains code to select gpu, I generally upload to colab. Save following code as script.py

import bpy, _cycles

bpy.context.scene.cycles.device = 'GPU'

avail_devices = _cycles.available_devices('CUDA')
print(avail_devices)

prop = bpy.context.preferences.addons['cycles'].preferences

prop.get_devices(prop.compute_device_type)
prop.compute_device_type = 'CUDA'

for device in prop.devices:
    if device.type == 'CUDA':
        print('device: ', device)
        device.use = True


this worked for me !